1. Field of the Invention
The present invention relates to a high-frequency knife (diathermic cutter) for excising a living tissue by high-frequency incision.
2. Description of the Related Art
There have been performed treatments in which a treatment instrument for incision is inserted in the body through, for example, a channel of an endoscope, and a living tissue such as a mucous membrane in the body is excised by the treatment instrument. A high-frequency treatment instrument (diathermic accessories) as disclosed in Jpn. Pat. Appln. KOKAI Pub. No. 4-329944 (Patent Document 1) is used for such an excision treatment.
The high-frequency treatment instrument disclosed in Patent Document 1 has an elongated inserting section, and a handheld operating section which is located on the side closer to the operator's hand and connected to a proximal end portion of the inserting section. The inserting section is inserted in the body through a channel of an endoscope. The inserting section has an elongated flexible tube having flexibility, and an operation wire which is axially-movably inserted into the flexible tube. The operating section has an operation handle. The operation wire is axially moved back and forth in synchronization with the operation of the operation handle. A needle-shaped knife section (electrode section) extending in the axial direction is provided on a distal end portion of the operation wire.
When the operation handle is operated, the operation wire is moved in the axial direction. By moving the operation wire, the knife section is projected from and retracted into the flexible tube. In this operation, the knife section is moved between a retracted position, where the knife section is housed in the flexible tube, and a use position where the knife section is projected outside the flexible tube. A living tissue contacting the knife section is cauterized and incised by the passage of a high-frequency current through the knife section, in the state where the knife section has been moved to the use position.
As a publicly-known non-patent document, there is Non-patent Document 1: Tuneo Oyama, et al., “Extended Adaptation of Stomach EMR: Contrivance and Results of Method Aimed at Large En-bloc Resection; Endoscopic Mucosal Resection Using a Hooking Knife”, Stomach and Intestine, August 2002, Vol. 37, No. 9, pp. 1155–1161. The Non-patent Document 1 discloses a high-frequency treatment instrument having a structure different from that disclosed in Patent Document 1. The high-frequency treatment instrument has a bent portion made by bending a distal end of its needle-shaped knife section (electrode section). In use of the high-frequency treatment instrument, a living tissue is hooked onto the bent portion of the knife section, and cauterized and incised while being pulled up by the bent portion.
As another publicly-known non-patent document, there is Non-patent Document 2: Haruhiro Inoue et al., “Endoscopic Mucosal Resection with a Cap-fitted Panendoscope for Stomach Cancer”, Endoscopia Digestiva, A to Z for How to Select Endoscopic Treatment Tools, September 2002, Vol. 14, No. 9, pp. 1301–1302. The Non-patent Document 2 discloses a high-frequency treatment instrument having another structure. The high-frequency treatment instrument has a disc-shaped electrode portion at a distal end of a needle-shaped knife section (electrode section). In use of the high-frequency treatment instrument, a living tissue is hooked onto the disk-shaped electrode portion of the knife section, and cauterized and incised while being pulled up by the disk-shaped electrode portion. Further, the disk-shaped electrode portion is pressed against a bleeding region, and thereby provides hemostasis to the bleeding region by coagulation.
If a living tissue is excised by using the high-frequency treatment instrument of the Patent Document 1, the knife section is stuck into a region to be excised, and then moved in a predetermined excision direction in the stuck state.
The following is an operation of excising a living tissue by using the high-frequency treatment instrument of Non-patent Document 1 or 2. The distal end of the knife section is inserted in a living tissue and pulled up, and thereby the living tissue is hooked onto the bent portion or the disk-shaped portion. This prevents the stuck knife portion from contacting a not-to-be-excised region.